In this research, product distribution and energy efficiency from co­gasification of pulp sludge mixed with black liquor has been suggested as a relatively new technology that can be used in addition to recovery boiler in the chemical recovery process. This research was carried out in a fixed bed reactor. The operating parameters including temperature of 700, 800 and 900°C, equivalence ratio (ER) of 0.2, 0.4 and 0.6 and ratio of pulp sludge to black liquor...